Everywhere, huh? Still plenty just running on VMs or serverless that don't need full blown container orchestration.
I'll agree that (nearly) everyone should know when Kubernetes is useful, but let's not pretend its the default method for everything. Even then, choosing to deploy on K8s falls on the sysadmins/DevOps I wouldn't expect the devs know or do much more than provide the Dockerfile.
Pretty close, they're very close to Heroku in spirit except the new wave of hosted backends (Vercel, and to a lesser extent Supabase and Cloudflare Workers) are much more tightly integrated with the app layer. You can almost think of them as libraries that run in the cloud which you can just use inside your app.